1. Field of the Invention
This invention relates to an operating shaft mechanism in a pushbutton tuner, and more particularly to a manual tuning shaft mechanism in a pushbutton tuner having a simple structure and capable of being mounted easily as well as being produced at low cost.
2. Description of the Prior Art
It is generally known that a pushbutton tuner has to be arranged not only to achieve tuning operation by pushing pushbuttons in a one-touch manner but also to perform fine tuning by rotating a manual tuning shaft.
A conventional tuning shaft which has been provided to this end is shown in FIG. 1. A shaft manually rotatable shaft 21 and a driven shaft 22 are connected to each other by a universal joint 24. The manual shaft 21 is rotatably supported in a casing 20 in a manner as shown in the drawing. The driven shaft 22 is provided with a pinion 22a at the right end thereof which engages with a crown gear 23. The manual shaft 21 and the driven shaft 22 are mounted in a manner so that they intersect at an angle with each other at the region of the universal joint 24. With this arrangement, by manually rotating the manual shaft 21 to rotate the crown gear 23 thus causing a core to shift in and out of a coil by means of a rotatable crank or a movable element, the desired fine tuning operation is performed.
However, in such a conventional mechanism, in addition to the fact that the shafts 21 and 22 are formed separately, there has been required the universal joint 24 which comprises two U-shaped elements mounted on the adjacent ends of the shafts 21 and 22, respectively, as well as a cross-shaped element interposed between the two U-shaped elements. That is, there has been required a large number of parts, resulting in an increase of the number of steps for assembling them. Further, those parts constructing the universal joint 24 have had to be made of a material with a high elasticity such as a phosphor bronze which is expensive.